Σύγκριση μεθόδων

	Έρευνα Τάσεων	Έρευνα Επιμήκους Τροχιάς
Πεδίο	Ερευνητικός Σχεδιασμός	Ερευνητικός Σχεδιασμός
Οικογένεια	Process / pipeline	Process / pipeline
Έτος προέλευσης	Mid-20th century (formalised in social science methodology ~1950s–1960s)	Late 19th–early 20th century; methodologically codified through the 20th century
Δημιουργός	Earl Babbie and survey research tradition	No single originator; foundational methodological treatments by Stuart Menard and Judith Singer & John Willett
Τύπος	Quantitative longitudinal research design	Quantitative (or mixed) observational research design
Θεμελιώδης πηγή	Creswell, J. W. (2014). Research Design: Qualitative, Quantitative, and Mixed Methods Approaches (4th ed.). Sage. ISBN: 978-1452226101	Menard, S. (2002). Longitudinal Research (2nd ed.). Sage Publications. ISBN: 978-0761922841
Εναλλακτικές ονομασίες	trend study, trend survey, longitudinal trend study, time-series survey	longitudinal study, longitudinal design, prospective longitudinal study, repeated-measures observational study
Συναφείς	4	4
Σύνοψη	Trend research is a longitudinal quantitative design that tracks changes in a characteristic of a general population over time by surveying different, independently drawn samples at two or more time points. Unlike panel studies, the same individuals are not followed; rather, each wave draws a fresh sample from the same population, allowing researchers to detect population-level shifts in attitudes, behaviours, or conditions while avoiding the attrition and panel conditioning problems of repeated-measures designs.	Longitudinal research is an observational design in which the same participants, groups, or units are measured repeatedly over an extended period. Rather than capturing a single snapshot, it tracks change, stability, and temporal sequencing of variables — making it the primary non-experimental strategy for studying development, growth, decline, and the unfolding of causal processes across time.